Householders have been warned not to sign energy contracts with cold-call companies that authorise them to switch supplier without notifying the householder.

The consumer markets authority AFM said it was receiving increasing numbers of complaints about telemarketing firms that ask householders to sign mandates – volmacht in Dutch – giving them decision-making powers.

Customers then find the company, typically a broker that shops around for the best deal for a customer, has changed their energy supplier without their knowledge – sometimes triggering penalties if they broke off a fixed contract before the end of its term.

Mandates are normally used in situations where people are unable to manage their own finances because of disabilities or infirmity, or to vote on someone else’s behalf if they are unable to get to a polling station.

ACM board member Manon Leijten said the mechanism was not meant to be used by companies providing commercial services.

“Telephone sales using mandates increase the risk of people being misled,” she said. “We see consumers and businesses being tied in to contracts that they did not choose themselves.”

The companies sometimes charge fees to revoke the mandate, which is prohibited by law, or cancel the contract, even though customers have the right to change their mind within 14 days without being penalised.

The ACM has warned in the past about telemarketing companies and advised people against agreeing energy contracts over the phone.

“Energy contracts are complicated products that you shouldn’t sign up to in an unsolicited phone call,” Leijten said.